Servosystem adapted for television tuning



w. E. FOSTER 2,812,486

SERVOSYSTEM ADAPTED FOR TELEVISION TUNING Nov. 5, 1957 5 Filed Spt. 17,1956 2 Sheets-Sheet 1 INVENTOR.

WALTER E. FOSTER.

INPUT TE RMXNALS 1 g. 7% A ri s.

Nov. 5, 1957 w. E. FOSTER 2,812,486

SERVOSYSTEM ADAPTED FOR TELEVISION TUNING Filed Sept. 17, 1956 2Sheets-Sheet 2 INVENTOR.

WALTER E. FOSTER.

'ATTORN' s.

United States Patent SERVOSYSTEM ADAPTED FQR TELEVISION TUNING WalterFoster, Bellevue, Ky., assignor to Avco Manufactoring Corporation,Cincinnati, Ohio, a corporation of Delaware Application September 17,,1956, Serial No. 610,162

7 Claims. (Cl. 318 467) The present invention relates to televisionreceivers and particularly to a novel device for controlling a step-typetelevision receiver tuner rapidly and conveniently and with a minimum ofeffort on the part of the operator.

An object of the invention is to provide a control device having suchoperation that the tuner of a television receiving set may be drivenstep by step to each one of its channel positions, for example, thetwelve V. H. F. positions for the twelve standard V. H. F. channels.Alternately, the device may be operated automatically to drive the tuneronly to the positions corresponding to the local stations in any area.The number of these local station positions is generally smaller; forexample, in Cincinnati there are three V. H. F. stations, numbered 5, 9and 12.

A further object of the invention is to provide, in combination, amotor-driven tuner, a manual mode-of-operation selector switch, a detentswitch, a pair of camactuated switches and instantaneous contacts, allso arranged that the motor may be actuated to drive the tuner step bystep or that the motor may be energized to drive the tuner to itspositions for the few local stations only.

For a better understanding of the invention, together with other andfurther objects, advantages and capabilities thereof, reference is madeto the following description of the accompanying drawings.

In the drawings,

Fig. 1 is a side elevational view, partly in section, showing atelevision receiver, otherwise of conventional character, in which thereis installed a control device in accordance with the invention;

Fig. 2 is a schematic diagram, partly in block form, partly in symbolicform, with cam and selector switch members shown in exploded view forpurposes of facilitating the explanation of the operation of theinvention;

Fig. 3 is a fragmentary front view showing the window on which thereappears a number indicative of the channel to which the tuner is tuned;

Fig. 4 is a top view of the manual mode-of-operation selector embodiedin the invention;

Fig. 5 is a perspective view of a spindle cam carrier and the spindlecams secured thereto;

Fig. 6 is a sectional view taken on line 6-6 of Fig. 1, looking in thedirection of the arrows, with certain parts broken away to facilitatedescription of the construction of the cams embodied in the invention;and

Fig. 7 is a sectional view taken on section line 77 of Fig. 6 andlooking in the direction of the arrows.

The invention is intended to be applied to or exploited in combinationwith a step tuner or one having a rotary turret. Tuners of this generalcharater are described in many publications, inclusive of the following:Television Engineering, pages 630, 633, Fink, McGraw-Hill Book Co., NewYork, 1952; Television Fundamentals, pages 104, 105, Fowler & Lippert,McGraw-Hill Book Co., New York, 1953.

A typical turret type of tuner with which my novel control device isfrequently used is the Standard Coil tuner, as described in TelevisionSimplified, pages 87-90,

2,812,486 Patented Nov. 5, 1957 Kiver, D. Van Nostrand Co., New York,1954. Tuners of this general character embody rotary selector switcheshaving a multiplicity of strongly detented positions. Substantial manualeifort is normally required to turn the turret from one station to thenext. The invention provides a means by which the tuner is electricallydriven, with speed and precision and without substantial effort on thepart of the operator.

In accordance with the invention, there is provided a novel controldevice for a step-type television receiver tuner. The device includes amotor 4 and a clutching arrangement 5 which mechanically couples thetuner drive shaft 8 to the motor. The motor is energized from aconventional source of power (not shown) connected to the inputterminals shown. In accordance with the invention, tuning isaccomplished by a three-position modeof-operation selector switch 46,etc., normally in the static position shown. The selector has twooperating positions into which it may be manually manipulated by theoperator in order instantaneously to connect the motor to the source toenergize the motor. That is, when the selector is in either itsclockwise position for step-by-step operation (closing contacts 43, 44)or in its counterclockwise position for automatic operation (closingcontacts 43, 45), the selector instantaneously connects motor and sourcethrough a first energizing circuit to initiate the driving of the tuner.The inventive combination also includes a first cam-switch means forcontinuing to energize the motor as it drives the shaft from one tunerchannel position to the next adjacent position and for stopping themotor after the tuner has turned through one position. This meanscomprises a cam 9, mounted on shaft 8, and a first switch (inclusive ofelements 14 and 19) controlled by the cam 9 (by reason of the operationof follower 16). The switch elements 14 and 19 are included in a secondcircuit, parallel to the first energizing circuit, between motor andsource for energizing the motor as it drives the shaft from one tunerchannel position to the next adjacent position. That is, theinstantaneous closing of contact 43 on either of contacts 44 or 45having caused clockwise rotation of cam 9, the first switch closes,assuring continuation of rotation until the next channel position of thetuner is reached. Cam 9 is so proportioned, by reason of its troughs, asto open the first switch at the conclusion of the desired rotation. Thefirst cam switch means, therefore, controls step-by-step operation.

In providing for automatic operationi. e., the selection of the fewlocal stations only-the invention further includes second cam-switchmeans for continuing the energizing of the motor as the turret turnsthrough several channels, as from one local station position to another.This means comprises a plurality of spindles 10 mounted on a cam carrier13, co-axial with cam 9. This means also comprises a second switch(including the elements 24 and 27) which is controlled by the cams 10 insuch a way that the motor is continuously energized as the tuner turnsfrom one local station position to another. The second switch is placedin circuit with the motor and source of power by the operation of athird or detent switch (including elements 41 and 42). The detent switchis positioned by the three-positioned mode-of-operation selector in sucha way that when the selector is placed in its automatic orcounterclockwise position, the detent switch is closed. When the detentswitch is closed, the second switch can be closed to energize the motorfor automatic operation. On the other hand, when the selector is in itsstep-by-step or clockwise position, then the detent switch is open. Thedetent switch and second switch are in a third parallel energizingcircuit between motor and source.

In Fig. 1, numeral 1 designates generally the television a 3 set havingthe usual picture tube 2. The receiver is provided with a step-typetuner 3, driven by an electric motor 4 through a gear reduction 5.Initiation of the operation of the motor,4 iseffected by closing of thecontacts 43, 44 or 43, 45 of the selector 46, etc., which closes thefirst parallel energizing circuit, while con tinued operation andstopping of the'motor are effected by cam-switch mechanismslFigs. 6 and7), which individually make and break second and third parallelenergizing circuits. These mechanisms are so arranged that step-by-stepor automatic operation is selected. In stepby-step operation, the motorstops at a channel position of the tuner by reason of the breaking ofcontacts17, 18 of the first switch and the opening of the secondparallel energizing circuit. In automatic operation, the motor stops ata local station position of the tuner by reason of the breaking ofcontacts 25, 26 of the second switch. I The output shaft 6 of the gearreduction is coupled to a clutch or coupling 7 (see Fig. 1), which, inturn, is coupled to the tuner shaft 8. The tuner shaft 8 extendsrearwardly of the set and has mounted at the rear end thereof themechanism of cam switches.

The step-by-step or first cam-switch mechanism includes a scalloped cam9, mounted on shaft 8. The automatic or second cam-switch mechanismincludes a cam-carrier 13, mounted on shaft 8, and a plurality ofspindlesor cams 10. The angular position of each spindle 10 coincideswith a tuner station position. As shown more particularly in Figs. 5 and6, the spindles 19 may be in 'the form of short studs which are threadedthrough openings 12 in the cam and cam-carrier 13. Being threaded,spindles 10 can individually be screwed inwardly into position to engagethe follower 22 on the switch controlled thereby (the second switch) andto keep the switch closed, or they may be retracted outwardly to aposition where they do not engage that fol lower and accordingly permitthe switch to open.

Associated with the scalloped cam 9 of the first camswitch mechanism isa switch member 14 of spring or leaf-like construction having at itsfree end a clip 15 for supporting a roller 16 which follows theundulations of the cam 9. The member 14 is provided with a contact 17disposed to make or break contact with a contact 18 on a switch member19. The switch members 14 and 19 are anchored in a bracket 20 carried bythe frame of the tuner as shown. The anchored ends of the switch membersare insulated from each other as at 21. The secured ends of these switchmembers 14 and 19 form the terminals of the first switch. As the cam 9rotates with its shaft 8, the contact member 17 engages contact member18 when the cam follower roller 16 passes over the crest of a lobe 11;these contacts separate or break the second energizing circuit when thefollower is in a trough between the crests of a pair of lobesi. e., whenthe tuner is in any one of its channel positions.

The spindles it of the second cam-switch mechanism project axiallyinwardly through the cam 9 and carrier 13 and are disposed to engage acam follower roller 22 carried by a bracket 23 at the free end of aspring switch member 24. Switch member 24 is provided with a contact 25disposed to engage a contact 26 on a switch member 27. The switchmembers 24 and 27 are secured at their fixed ends in a bracket 28 of theframe associated with the tuner and are insulated from each other byinsulation 29. The fixed ends of the switch blade members 24 and 27 formthe terminals whereby the contacts 25 and 26 may be caused to performthe circuit-controlling function for automatic operation. Contacts 25and 26 separate or break the third energizing circuit when the tuner isin one of its selected local-station positions, characterized byretraction of the corresponding spindle 10.

The switch members 24 and 27 of the second camswitch mechanism controllocal station selection with automatic tuning. If, for example, thetelevision set is used in an area where the station channels areidentified by channel numbers 3, 5 and 10, then the spindles 10corresponding to those numbers are screwed to the re tracted positionwith respect to cam 9 and cam carrier 13 so as to be out of the path ofengagement with the cam follower roller 22. Therefore, when the camcarrier 13 rotates to an angular position where there is no spindle toengage the cam follower 22, the switch contact members 25 and 26 of thesecond cam-switch mechanism move to open position and interrupt thepower to the motor by opening the third parallel energizing circuit.

In Fig. 2 the circuitry for the motor and the cam switches isillustrated schematically. Motor 4 may be a two-pole shaded pole motorand provided with a solenoid armature 30. The armature as shown isnormally urged out of its central magnetic position with reference tothe field poles of the motor by means of a spring 31 disposed betweenthe housing of the gear reduction 5 and the frame or housing 32 of themotor. The shaft 33 of the armature 30 is journaled in bearings 34 and35, as shown. The end of the motor shaft 33 that extends into thehousing of the gear reduction is provided with a cone gear or pinion 36.When the motor is d e-energized, that pinion is disengaged by spring 31from a driven gear 37, thereby preventing over-running of the tuner thatcould result if the pinion were not disengaged. The driven gear 37 is inthe chain of gears that ultimately lead to the driven or output shaft 6.

When the motor is energized, the field of the motor pulls the armatureto the right, as viewed in Fig. 2, causing the gear 36 to mesh with themating gear 37, whereupon the tuner shaft 3 is clutched to the motor anddriven. In Fig. 2 the cam 9 and the spindle carrier 13 are shownseparated, that is, in an exploded view. When cam 9 is in the particularangular position shown, cam follower roller 16 of switch member 14 liesin a trough between a pair of lobes of cam 9. Therefore, the switchcontact members 17 and 18 of the first switch are disengaged. When thecam follower roller 22 is in engagement with one of the spindles, thecontact members 25 and 26 of the second switch are in engagement.

The mode-of-operation selector is provided with contacts 43 and 4445 forenergizing the motor through a first energizing path parallel with thesecond and third paths of cam switches 14, 19 and 24, 27, respectively,whereby motor 4 may be caused to initiate operation (when such contactsare instantaneously closed). The selector also includes a detent switch(having contacts 41 and 42) in series with the second cam switch 24, 27,which cam switch operates to stop the motor and tuner at one of thelocal station positions. The detent switch, a part of the selector,performs the function of setting up the second switch circuit whenautomatic operation is desired and cutting out that circuit whenstep-by-step operation is called for. In local station or automaticoperation, the pairs of contacts 43 and 45 and 41, 42 are momentarilyclosed, the motor starts and contacts 41, 42 remain closed so that themotor does not stop until the second cam switch 24, 27 opens. Switch 24,27 opens when the angular position of cam carrier 13 and shaft 8 and thetuner are such that roller 22 registers with a retracted spindle, i. e.,when the tuner is on a local station. To re-energize the motor and turnthe tuner turret beyond that stopping point, the contacts 43, 45 of theselector are momentarily closed, thereby effecting re-energization ofthe motor and a resumption of its operation until the next local stationis reached, at which time the motor will again stop.

The arrangements for automatic control in the selector comprise thedetent switch having contact members 41 and 42. The member 41 andcontact 43 are actuated by a rocker member 46 mounted on a pivot 47 andnormally urged to a neutral position by springs 48 and 49 that engagemember 46 on opposite sides of the pivot 47. The rocker member 46 isprovided with spaced lugs 50 for operating detent switch 41 either toopen or closed position with reference to its stationary contact member42. When switch member 41 has been actuated to either of these positionsby lugs 50 and the rocker member 46 has been released, the rockerreturns to neutral position, but switch member 41 remains in theposition to which it had been actuated until reactuated by lugs 50.

When the rocker member 46 is actuated to engage switch member 43 withcontact member 44, detent switch member 41 will be opened if in theclosed position, and the motor 4 is connected to the power sourcerepresented by the input terminals. The motor will remain connected tothe power source by the operator only so long as the switch member 43 isin engagement with contact 44. Momentary contact between member 43 andcontact member 44 is suificient to insure operation of the motor 4because a second parallel circuit for the motor is maintained throughthe closed contact members of switch members 14 and 19 even aftercontacts 43 and 44 separate. That is, as soon as the motor starts tooperate, one of the lobes 11 will close the contacts of step-by-stepcontrol switch members 14 and 19 and maintain a closed motor circuituntil the cam follower roller 16 drops into the valley between the nextpair of lobes.

When the rocker member 46 is turned counter-clockwise on its pivot, thedetent switch is closed on its stationary contact member 42. Further,the switch member 43 momentarily engages contact member 45, therebymomentarily energizing, motor 4 and causing it to operate through thefirst parallel energizing circuit established by the closing of contact41 on its contact 42. Upon release of the rocker 46, contacts 43, 45open but the motor continues running, by reason of the closing of thethird parallel energizing circuit, until the spindle cam or automaticswitch 24, 27 opens at a dead spot where there is no spindle to engagethe cam follower 22. That stopping point or angular position wouldindicate or correspond with one of the tuner positions for localstations available in a particular area where the receiver is beingoperated. If that station is not the one desired, the next local stationmay be selected by merely momentarily closing the contact member 43 oncontact member 45 and at the same time reclosing the detent switchcontact 41 on contact member 42.

The selector is mounted in an escutcheon plate or bar 55 located at thefront of the top of the cabinet of the receiver 1, as shown in Figs. 1and 4. The escutcheon plate or bar 55' is provided at one end with anon-and-off switch 56 whereby the power input to the television set andto the motor input terminals may be controlled. At the opposite end ofthe plate or bar 55 the selector is mounted. By merely tilting therocker 46 of the selector either counter-clockwise or clockwise, asviewed in Fig. l, the tuner mechanism may be operated to selectautomatically the local stations, or it may be operated step-by-step, asdescribed supra.

The receiver shown also is provided with an illuminated channelindicator that is operated by the drive mechanism for the tuner 3. Asshown in Fig. 1, the television tube 2 is mounted at the front in aframe or border 57 provided with a tubular boss 58 in the outer end ofwhich is a translucent screen 59 as disclosed in my co-pendingapplication for patent, Serial No. 568,473, filed February 29, 1956,assigned to Avco Manufacturing Corporation and entitled ChannelIndicators for Television Receivers. The screen 59 indicates by means ofan illuminated digit the particular station to which the set has beentuned, and that illuminated digit may be visible by a viewer from anypoint from which the picture on the screen of the tube may be seen. Thechannel indication which appears on the screen 53- derives from arotatable disk 60 having near the perimeter thereof apertures which areformed in the shape of the particular digits. The digits may run from 1to 12 or any other desired number. The disk 60 is mounted on a shaft 61.journaled in a frame 62. Between the tuner and the disk is a lightsource 63 which is focused to project light rays through the particularaperture that comes into register with its beam 64. The light beamshining through a digit causes the outline or form of the digit toappear on the translucent screen. The shaft 61 of disk 60 is driven bythe output shaft of the gear reduction 5 through a flexible cable 66.

The light source 63 may be mounted on any suitable support, preferablyas shown in my co-pending application above mentioned, wherein means isprovided for adjusting the position of the light bulb so that itproperly focuses with the digits on the circular disk and the screen.

Recapitulating, the television receiver is provided with amode-of-operation selector 46, etc. (Fig. 2). This selector has threepositions: An inactive position to which it is normally biased bysprings 48 and 49; and two operating positions. The clockwise operatingposition is for stepby-step operation. That is, the operator simplydepresses the teeter-totter selector in a clockwise direction. When thisis done instantaneously, the tuner simply moves one step to the nextchannel and stops. On the other hand, if the operator continues to holdcontact 43 against contact 44 by keeping his hand on the switch, thenthe device continues to move step by step until the hand is removed,breaking contacts 43, 44. During this type of operation a lug 50separates the contacts 41, 42 and prevents automatic operation. It willbe seen that the operation of contacts 43, 44 and the closing of thefirst energizing circuit start the motor 4, but the motor 4 continues inoperation for one step by reason of the operation of cam 9, which closesa second parallel motor-energizing circuit through switch contacts 14,19. When the tuner has reached the next step or station or position, theswitch 14 and 19 opens.

Now let us further briefly consider automatic operation. When theteeter-totter selector 46, etc., is instantaneously manually depressedinto the counter-clockwise position, the motor action is initiallyenergized by the closing of contacts 43, 45, which function in the samemanner as the contacts 43, 44. Now a third circuit, made up of theseries elements 41, 42 and 24, 27, enters into the picture. Theseelements, functioning together as a closed circuit during automaticoperation, furnish a third parallel energizing circuit to the motorbetween local station positions. As has been shown, this circuit isde-energized by the opening of switch 24, 27 when a local channelposition is indicated by retraction of the corresponding spindle 10.

To repeat, for either type of operation the motor is firstinstantaneously started by appropriate motion of contact 43. In eithertype of operation the motor is caused to move the tuner step by step bythe action of cam 9 and first switch 14, 19. On automatic operation themotor is caused to run for several successive steps by reason of theoperation of carrier 13, spindles 10, the second switch 24, 27, and thedetent switch 41, 42, the latter always being closed during automaticoperation.

Having thus described the invention, it will be apparent to those ofordinary skill in the art to which the invention pertains that variousmodifications and changes may be made in the illustrated embodimentwithout departing from either the spirit or the scope of the invention.

Therefore, what is claimed as new and desired to be secured by LettersPatent is:

1. A control device for a step-type television receiver tuner,comprising a motor and tuner shaft for driving the tuner, a source ofpower, a three-position mode-of-operation selector having contacts incircuit with said motor and normally having a neutral position, butoperable in either of two other positions instantaneously to close saidcontacts and connect the motor to the source to energize the motor, andmeans responsive to angular shaft displacement for continuing toenergize the motor as the shaft turns between successive predeterminedchannel positions of the tuner, the last-mentioned means comprising acam mounted on the tuner shaft and a switch controlled by the cam andinclusive of contact elements between motor and source, the last-namedcontact elements being made to energize the motor, the cam being soproportioned as to open the switch and stop the shaft and tuner bybreaking such contact elements at any tuner channel position.

2. A control device for a television receiver tuner, com prising a motorand shaft for driving the tuner, 21 source of power, a three-positionmode-of-operati'on selector having contacts in circuit with said motorand normally having a neutral position, but operable in another positioninstantaneously to close said contacts and connect the motor to thesource through a first circuit to energize the motor, and cam-switchmeans including a rotatably mounted cam controlled by the shaft forcontinuing to energize the motor through a second parallel circuit asthe shaft turns from one channel position of the tuner to the nextadjacent position.

3. A control device for a step-type television receiver tuner,comprising a motor and shaft for driving the tuner, a source of powerand a three-position mode-of-operation selector having contacts inseries with said motor and normally having a neutral position, butoperable in either of two other positions instantaneously to connect themotor to the source to energize the motor, means responsive to angularshaft displacement for continuing to energize the motor as the shaftturns from one channel position of the tuner to the next adjacentposition, the lastmentioned means comprising a cam mounted on the shaftand a switch controlled by the cam and inclusive of contact elementsbetween motor and source, which contact elements are made for energizingthe motor to drive the shaft from one tuner channel position to the nextadjacent position, the cam being so proportioned as to open the switchand stop the shaft by breaking such contact elements at any tunerchannel position, means responsive to angular shaft displacement forcontinuously energizing the motor as the shaft turns between successiveselected local station positions of the tuner, the last-mentioned meanscomprising other cams secured to the shaft and a switch controlled bysuch other cams and inclusive of contact elements between motor andsource, which last-named contact elements are made for energizing themotor between local station positions of the tuner, said other camsbeing so constructed and arranged as to open the last-mentioned switchin any local station tuner position, and an on-off detent switch inseries with the last-mentioned switch and controlled by the selector tobe turned on when the selector is in one operating position and off whenthe selector is in its other operating position.

4. A control device for a television receiver tuner,

comprising a motor and shaft for driving the tuner, a

source of power and a three-position mode-of-operation selector normallyhaving a neutral position, but operable in either of two other positionsinstantaneously to connect the motor to the source to energize the motorthrough a first circuit, cam-switch means including a rotatably mountedcam controlled by the shaft for continuing to energize the motor througha second circuit as the shaft turns from one channel position of thetuner to the next adjacent channel position, other cam-switch means including another rotatably mounted cam controlled by the shaft forcontinuing to energize the motor through a third circuit as the shaftturns between successive local station positions of the tuner, andswitch means controlled by the selector for activating one of thecam-switch means when the selector is in one operating position and bothcam-switch means when it is in the other operating position.

5. A control device for a television receiver tuner, comprising meansfor driving the tuner, a source of power and a three-positionmode-of-operation selector normally having a neutral position, butoperable in either of two other positions instantaneously to connect thedriving means to the source to energize the driving means, meansincluding a rotatably mounted cam and responsive to initial movement ofthe driving means for continuing the drive from one channel position ofthe tuner to the next adjacent channel position, means including anotherrotatably mounted cam and responsive to initial movement of the drivingmeans for continuing the drive between successive local stationpositions of the tuner, and means included in the selector for selectingeither of the lastmentioned two means.

6. A switch mechanism for so controlling the operation of a motordisposed to drive a driven element as to provide controlled step-by-stepand selective interruptions in the operation of the motor, comprising amotor, parallel circuit-connected switches in circuit with the motor,separate rotatably mounted cam means for operating each of saidswitches, one of said cams having uniformly spaced lobes forstep-by-step operation, and the other of said cams being provided withpreselectable skip means, whereby the number and location of theinterruptions may be predetermined at will, and a mode-ofoperationselector including momentary circuit-closing means in circuit with themotor and in shunt relation to the switches for initiating step-by-stepor continuous energization of the motor circuit at will.

7. A motor-driven tuner for a television receiver, comprising a tunerhaving a rotating element, a gear reduction unit having an input shaftand pinion and an output shaft connected to the rotary element of thetuner, a motor having a solenoid armature and a shaft coupled to theinput shaft of the gear reduction, whereby the pinion is engaged with ordisengaged from its driven gear upon energization or de-energization ofthe motor, a manually operable detent switch and momentarycircuit-making means, a pair of rotatably mounted cams driven by thetuner and secured to its rotating element, one of said cams havinguniformly spaced lobes, the other cam having uniformly spaced cammembers which may be preselectively placed in or out of operativecondition, a switch for each cam, the switch associated with the lobecam being in parallel with the momentary circuitmaking means anddisposed to maintain the motor circuit for intervals equal to thespacings between adjacent lobes, and the other cam switch being inseries with the detent 'switch and disposed to maintain the motorcircuit until its cam has rotated to a point where a cam member is outof operative condition with respect thereto.

References Cited in the file of this patent UNITED STATES PATENTS1,775,730 McNichol Sept. 16, 1930 2,725,512 Padron Nov. 29, 19552,794,162 Lifsey May 28, 1957

